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| United States Patent |
5,726,356
|
|
Kukita
, et al.
|
March 10, 1998
|
Testing apparatus for combustible charge intake system
Abstract
A testing apparatus for a combustible charge intake system of an internal
combustion engine, including a throttle position sensor and a throttle
switch respectively coupled with a throttle valve, an accelerator switch
coupled with an accelerator pedal, and a control unit operatively coupled
with the switches. The control unit is operative to determine that the
throttle valve has failed to operate normally when the throttle switch
fails to shift to its predetermined state after the accelerator switch has
shifted to its predetermined state. The control unit is operative to
determine that the accelerator switch fails to operate normally in
response to the control unit determining that the accelerator switch has
failed to take the predetermined state thereof after the throttle switch
has been in the predetermined state thereof.
| Inventors:
|
Kukita; Hiroshi (Yokohama, JP);
Muraki; Hirotada (Atsugi, JP)
|
| Assignee:
|
Nissan Motor Co., Ltd. (Kanagawa, JP)
|
| Appl. No.:
|
674235 |
| Filed:
|
June 28, 1996 |
Foreign Application Priority Data
| Current U.S. Class: |
73/118.2 |
| Intern'l Class: |
F02D 009/02 |
| Field of Search: |
73/118.1,118.2,116,117.3
123/399
|
References Cited
U.S. Patent Documents
| 4437342 | Mar., 1984 | Hosaka et al.
| |
| 5074267 | Dec., 1991 | Ironside et al. | 123/399.
|
| 5079946 | Jan., 1992 | Motamedi et al. | 73/118.
|
| 5137004 | Aug., 1992 | Takahata et al.
| |
| 5159831 | Nov., 1992 | Kitagawa et al. | 73/118.
|
| 5193506 | Mar., 1993 | Ironside et al. | 123/399.
|
| 5255653 | Oct., 1993 | Ironside et al. | 123/399.
|
| 5321980 | Jun., 1994 | Hering et al. | 73/118.
|
| 5447134 | Sep., 1995 | Yokoyama | 73/118.
|
| 5521825 | May., 1996 | Unuvar et al. | 73/118.
|
| Foreign Patent Documents |
| 121 937 A1 | Oct., 1984 | EP.
| |
| 4312336 A1 | Mar., 1997 | DE.
| |
| 5-296097 | Nov., 1993 | JP.
| |
Primary Examiner: Dougherty; Elizabeth L.
Assistant Examiner: McCall; Eric S.
Attorney, Agent or Firm: Lowe, Price, LeBlanc & Becker
Claims
What is claimed is:
1. In a testing apparatus for a combustible charge intake system of an
internal combustion engine, including a power control element positionable
in response to a control signal to establish various states of combustible
charge to be combusted in the internal combustion engine, a position
sensor operatively coupled with the power control element to provide an
actual position signal indicative of a position which the power control
element takes, a control unit for developing the control signal as a
predetermined function of a position of an accelerator pedal, a first
switch shiftable to a predetermined state in response to the accelerator
pedal moving below a predetermined position, and a second switch shiftable
to a predetermined state when a position which the power control element
takes is less than a predetermined position, the control unit being
operatively coupled with the first and second switches,
the improvement wherein the control unit is operative to determine whether
or not the actual position signal is equal to or less than a predetermined
value;
the control unit is operative to determine whether or not the second switch
is in the predetermined state thereof after the control unit determining
that the actual position signal has been equal to or less than said
predetermined value;
the control unit is operative to determine whether or not the first switch
fails to take the predetermined state thereof after the control unit
determining that the second switch has been in the predetermined state
thereof;
the control unit is operative to determine that the first switch fails to
operate normally in response to the control unit determining that the
first switch has failed to take the predetermined state thereof after the
second switch has been in the predetermined state thereof;
the control unit is operative to determine whether or not the actual
position signal continues to be equal to or less than said predetermined
value for a first predetermined period of time; and
the control unit is operative to determine whether or not the second switch
continues to take the predetermined state thereof for a second
predetermined period of time after the control unit determining that the
actual position signal has continued to be equal to or less than said
predetermined value for said first predetermined period of time.
2. The improvement as claimed in claim 1, wherein the control unit is
operative to determine whether or not the first switch continues to fail
to take the predetermined state thereof for a third predetermined period
of time after the control unit determining that the second switch has
continued to take the predetermined state thereof for said second
predetermined period of time.
3. The improvement as claimed in claim 2, wherein the control unit is
operative to determine that the first switch fails to operate normally in
response to the control unit determining that the first switch has
continued to fail to take the predetermined state thereof for said third
predetermined period of time after the second switch has continued to take
the predetermined state thereof for said second predetermined period of
time.
4. In a testing apparatus for a combustible charge intake system of an
internal combustion engine, including a power control element positionable
in response to a control signal to establish various states of combustible
charge to be combusted in the internal combustion engine, a position
sensor operatively coupled with the power control element to provide an
actual position signal indicative of a position which the power control
element takes, a control unit for developing the control signal as a
predetermined function of a position of an accelerator pedal, a first
switch shiftable to a predetermined state in response to the accelerator
pedal moving below a predetermined position, and a second switch shiftable
to a predetermined state when a position which the power control element
takes is less than a predetermined position, the control unit being
operatively coupled with the first and second switches and operative to
determine that the power control element has failed to operate normally
when the second switch fails to shift to the predetermined state thereof
after the first switch has shifted to the predetermined state thereof,
the improvement wherein the control unit is operative to determine whether
or not the actual position signal is equal to or less than a predetermined
value;
the control unit is operative to determine whether or not the second switch
is in the predetermined state thereof after the control unit determining
that the actual position signal has been equal to or less than said
predetermined value;
the control unit is operative to determine whether or not the first switch
fails to take the predetermined state thereof after the control unit
determining that the second switch has been in the predetermined state
thereof;
the control unit is operative to determine that the first switch fails to
operate normally in response to the control unit determining that the
first switch has failed to take the predetermined state thereof after the
second switch has been in the predetermined state thereof;
the control unit is operative to determine whether or not the actual
position signal continues to be equal to or less than said predetermined
value for a first predetermined period of time; and
the control unit is operative to determine whether or not the second switch
continues to take the predetermined state thereof for a second
predetermined period of time after the control unit determining that the
actual position signal has continued to be equal to or less than said
predetermined value for said first predetermined period of time.
5. The improvement as claimed in claim 4, wherein the control unit is
operative to determine whether or not the first switch continues to fail
to take the predetermined state thereof for a third predetermined period
of time after the control unit determining that the second switch has
continued to take the predetermined state thereof for said second
predetermined period of time.
6. The improvement as claimed in claim 5, wherein the control unit is
operative to determine that the first switch fails to operate normally in
response to the control unit determining that the first switch has
continued to fail to take the predetermined state thereof for said third
predetermined period of time after the second switch has continued to take
the predetermined state thereof for said second predetermined period of
time.
7. A testing apparatus for a combustible charge intake system of an
internal combustion engine including a power control element positionable
in response to a control signal to establish various states of combustible
charge to be combusted in the internal combustion engine, a position
sensor operatively coupled with the power control element to provide an
actual position signal indicative of a position which the power control
element takes, a control unit for developing the control signal as a
predetermined function of a position of an accelerator pedal, a first
switch shiftable to a predetermined state in response to the accelerator
pedal moving below a predetermined position, and a second switch shiftable
to a predetermined state when a position which the power control element
takes is less than a predetermined position;
wherein the control unit is operatively coupled with the first and second
switches;
the control unit is operative to determine whether or not the actual
position signal is equal to or less than a predetermined value;
the control unit is operative to determine whether or not the second switch
is in the predetermined state thereof after the control unit determining
that the actual position signal has been equal to or less than said
predetermined value;
the control unit is operative to determine whether or not the first switch
fails to take the predetermined state thereof after the control unit
determining that the second switch has been in the predetermined state
thereof;
the control unit is operative to determine that the first switch fails to
operate normally in response to the control unit determining that the
first switch has failed to take the predetermined state thereof after the
second switch has been in the predetermined state thereof; and
the control unit is operative to conduct a test routine, when the control
unit determines that the first switch operates normally, to determine
whether or not the power control element operates normally wherein the
control unit determines that the power control element has failed to
operate normally when the second switch fails to shift to the
predetermined state thereof after the first switch has shifted to the
predetermined state thereof.
8. The testing apparatus as claimed in claim 7, wherein the control unit is
operative to determine whether or not the actual position signal continues
to be equal to or less than said predetermined value for a first
predetermined period of time.
9. The testing apparatus as claimed in claim 8, wherein the control unit is
operative to determine whether or not the second switch continues to take
the predetermined state thereof for a second predetermined period of time
after the control unit determining that the actual position signal has
continued to be equal to or less than said predetermined value for said
first predetermined period of time.
10. The testing apparatus as claimed in claim 9, wherein the control unit
is operative to determine whether or not the first switch continues to
fail to take the predetermined state thereof for a third predetermined
period of time after the control unit determining that the second switch
has continued to take the predetermined state thereof for said second
predetermined period of time.
11. The testing apparatus as claimed in claim 10, wherein the control unit
is operative to determine that the first switch fails to operate normally
in response to the control unit determining that the first switch has
continued to fail to take the predetermined state thereof for said third
predetermined period of time after the second switch has continued to take
the predetermined state thereof for said second predetermined period of
time.
12. The testing apparatus as claimed in claim 7, wherein the internal
combustion engine is a gasoline engine.
13. The testing apparatus as claimed in claim 7, wherein the internal
combustion engine is a diesel engine.
14. A testing method for a combustible charge intake system of an internal
combustion engine, including a power control element positionable in
response to a control signal to establish various states of combustible
charge to be combusted in the internal combustion engine, a position
sensor operatively coupled with the power control element to provide an
actual position signal indicative of a position which the power control
element takes, a control unit for developing the control signal as a
predetermined function of a position of an accelerator pedal, a first
switch shiftable to a predetermined state in response to the accelerator
pedal moving below a predetermined position, and a second switch shiftable
to a predetermined state when a position which the power control element
takes is less than a predetermined position, the control unit being
operatively coupled with the first and second switches and operative to
determine that the power control element has failed to operate normally
when the second switch fails to shift to the predetermined state thereof
after the first switch has shifted to the predetermined state thereof, the
testing method comprising the steps of:
determining whether or not the actual position signal is equal to or less
than a predetermined value;
determining whether or not the second switch is in the predetermined state
thereof after the control unit determining that the actual position signal
has been equal to or less than said predetermined value;
determining whether or not the first switch fails to take the predetermined
state thereof after the control unit determining that the second switch
has been in the predetermined state thereof; and
determining that the first switch fails to operate normally in response to
the control unit determining that the first switch has failed to take the
predetermined state thereof after the second switch has been in the
predetermined state thereof.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a testing apparatus for a combustible
charge intake system of an internal combustion engine.
There has been proposed or known a combustible charge intake system of an
internal combustion engine including a power control element, e.g., a
throttle valve in the case of a gasoline engine or an adjusting lever of a
fuel injection pump in the case of a diesel engine, positionable by an
actuator in response to a control signal to establish various states of
combustible charge to be combusted in the engine. A control unit is
operatively coupled with a position sensor operatively coupled with the
power control element and an accelerator position sensor operatively
coupled with an accelerator or gas pedal manipulable by an operator. The
control unit develops the control signal as a predetermined function of a
position or a degree of depression of the accelerator pedal.
In order to enhance reliability of or safeguard the system of this kind,
Japanese Patent Application First Publication No. 5-296097 discloses a
testing apparatus for conducting a test routine to determine whether or
not the throttle valve operates normally and produces an alarm if the
throttle valve fails to operate normally. The test involves a logic that
the throttle valve fails to operate normally when a throttle switch fails
to shift to its closed position after an accelerator switch has shifted to
its closed position. The throttle switch is designed to be closed when the
throttle valve is closed, while the accelerator switch is designed to be
closed when the accelerator pedal is released.
An object of the present invention is to enhance reliability of a testing
apparatus of the above kind.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided, in a
testing apparatus for a combustible charge intake system of an internal
combustion engine, including a power control element positionable in
response to a control signal to establish various states of combustible
charge to be combusted in the internal combustion engine, a position
sensor operatively coupled with the power control element to provide an
actual position signal indicative of a position which the power control
element takes, a control unit for developing the control signal as a
predetermined function of a position of an accelerator pedal, a first
switch shiftable to a predetermined state in response to the accelerator
pedal moving below a predetermined position, and a second switch shiftable
to a predetermined state when a position which the power control element
takes is less than a predetermined position, the control unit being
operatively coupled with the first and second switches,
the improvement wherein the control unit is operative to determine whether
or not the actual position signal is equal to or less than a predetermined
value;
the control unit is operative to determine whether or not the second switch
is in the predetermined state thereof after the control unit determining
that the actual position signal has been equal to or less than the
predetermined value;
the control unit is operative to determine whether or not the first switch
fails to take the predetermined state thereof after the control unit
determining that the second switch has been in the predetermined state
thereof; and
the control unit is operative to determine that the first switch fails to
operate normally in response to the control unit determining that the
first switch has failed to take the predetermined state thereof after the
second switch has been in the predetermined state thereof.
According to another aspect of the present invention, there is provided, in
a testing apparatus for a combustible charge intake system of an internal
combustion engine, including a power control element positionable in
response to a control signal to establish various states of combustible
charge to be combusted in the internal combustion engine, a position
sensor operatively coupled with the power control element to provide an
actual position signal indicative of a position which the power control
element takes, a control unit for developing the control signal as a
predetermined function of a position of an accelerator pedal, a first
switch shiftable to a predetermined state in response to the accelerator
pedal moving below a predetermined position, and a second switch shiftable
to a predetermined state when a position which the power control element
takes is less than a predetermined position, the control unit being
operatively coupled with the first and second switches and operative to
determine that the power control element has failed to operate normally
when the second switch fails to shift to the predetermined state thereof
after the first switch has shifted to the predetermined state thereof,
the improvement wherein the control unit is operative to determine whether
or not the actual position signal is equal to or less than a predetermined
value;
the control unit is operative to determine whether or not the second switch
is in the predetermined state thereof after the control unit determining
that the actual position signal has been equal to or less than the
predetermined value;
the control unit is operative to determine whether or not the first switch
fails to take the predetermined state thereof after the control unit
determining that the second switch has been in the predetermined state
thereof; and
the control unit is operative to determine that the first switch fails to
operate normally in response to the control unit determining that the
first switch has failed to take the predetermined state thereof after the
second switch has been in the predetermined state thereof.
According to still another aspect of the present invention, there is
provided a testing apparatus for a combustible charge intake system of an
internal combustion engine including a power control element positionable
in response to a control signal to establish various states of combustible
charge to be combusted in the internal combustion engine, a position
sensor operatively coupled with the power control element to provide an
actual position signal indicative of a position which the power control
element takes, a control unit for developing the control signal as a
predetermined function of a position of an accelerator pedal, a first
switch shiftable to a predetermined state in response to the accelerator
pedal moving below a predetermined position, and a second switch shiftable
to a predetermined state when a position which the power control element
takes is less than a predetermined position;
wherein the control unit is operatively coupled with the first and second
switches;
the control unit is operative to determine whether or not the actual
position signal is equal to or less than a predetermined value;
the control unit is operative to determine whether or not the second switch
is in the predetermined state thereof after the control unit determining
that the actual position signal has been equal to or less than the
predetermined value;
the control unit is operative to determine whether or not the first switch
fails to take the predetermined state thereof after the control unit
determining that the second switch has been in the predetermined state
thereof;
the control unit is operative to determine that the first switch fails to
operate normally in response to the control unit determining that the
first switch has failed to take the predetermined state thereof after the
second switch has been in the predetermined state thereof; and
the control unit is operative to conduct a test routine, when the control
unit determines that the first switch operates normally, to determine
whether or not the power control element operates normally wherein the
control unit determines that the power control element has failed to
operate normally when the second switch fails to shift to the
predetermined state thereof after the first switch has shifted to the
predetermined state thereof.
According to still another aspect of the present invention, there is
provided a testing method for a combustible charge intake system of an
internal combustion engine, including a power control element positionable
in response to a control signal to establish various states of combustible
charge to be combusted in the internal combustion engine, a position
sensor operatively coupled with the power control element to provide an
actual position signal indicative of a position which the power control
element takes, a control unit for developing the control signal as a
predetermined function of a position of an accelerator pedal, a first
switch shiftable to a predetermined state in response to the accelerator
pedal moving below a predetermined position, and a second switch shiftable
to a predetermined state when a position which the power control element
takes is less than a predetermined position, the control unit being
operatively coupled with the first and second switches and operative to
determine that the power control element has failed to operate normally
when the second switch fails to shift to the predetermined state thereof
after the first switch has shifted to the predetermined state thereof, the
testing method comprising the steps of:
determining whether or not the actual position signal is equal to or less
than a predetermined value;
determining whether or not the second switch is in the predetermined state
thereof after the control unit determining that the actual position signal
has been equal to or less than the predetermined value;
determining whether or not the first switch fails to take the predetermined
state thereof after the control unit determining that the second switch
has been in the predetermined state thereof; and
determining that the first switch fails to operate normally in response to
the control unit determining that the first switch has failed to take the
predetermined state thereof after the second switch has been in the
predetermined state thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a testing apparatus for a combustible charge
intake system of a gasoline engine;
FIGS. 2A and 2B are a flow diagram of a test routine to determine whether
an accelerator switch fails to operate normally during an engine
operation;
FIG. 3 is a graphic diagram illustrating a relation between a throttle
valve position, a throttle switch, and the accelerator switch;
FIG. 4 is a block diagram of a testing apparatus for a combustible charge
intake system of a diesel engine;
FIG. 5 is a fragmentary view, partly in section, of a fuel injection pump
of the diesel engine shown FIG. 5; and
FIG. 6 is a flow diagram of a test routine to determine whether a throttle
valve fails to operate normally during an engine operation.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, there is illustrated a first embodiment of a testing
apparatus for a combustible charge intake system of an internal combustion
engine. In this embodiment, the internal combustion engine is a gasoline
engine 10.
As illustrated in FIG. 1, the gasoline engine 10 includes an air induction
passage 12. A throttle valve 14 is disposed within the air induction
passage 12. The throttle valve 14 acts as a power control element
positionable in response to a control signal to establish various states
of combustible charge to be combusted in the gasoline engine 10. An
actuator 16, e.g. stepping motor or direct current motor, is provided for
actuating the throttle valve 14 to control an amount of intake air flowing
to the air induction passage 12. A throttle position sensor 18 is
operatively coupled with the throttle valve 14 to provide an actual
position signal .theta.A indicative of a position which the throttle valve
14 takes. The position of the throttle valve 14 is indicated by a value of
opening degree of the throttle valve 14. A throttle switch 20 is so
disposed and arranged as to be shiftable to a predetermined state when the
position which the throttle valve 14 takes is less than a predetermined
position. In this embodiment, the predetermined state of the throttle
switch 20 is a closed state, namely an ON state. The throttle switch 20
generates a signal TSS while it is in the ON state. An accelerator or gas
pedal 22 is so disposed as to be moveable between a released position and
a fully depressed position in response to operator power demand. An
accelerator position sensor 24 is operatively coupled with the accelerator
pedal 22 to detect a position which the accelerator pedal 22 takes and
generate a position signal .theta.B indicative of the position thereof. An
accelerator switch 26 is so disposed and arranged as to be shiftable to a
predetermined state in response to the accelerator pedal 22 moving below a
predetermined position. In this embodiment, the predetermined state of the
accelerator switch 28 is a closed state, namely an ON state in which the
accelerator pedal 22 reaches the released position. The accelerator switch
28 generates a signal ASS while it is in the ON state. An alarm light 27
is provided for indicating that the accelerator switch 26 fails to operate
normally. An engine revolution sensor 28 is provided for detecting the
number of revolution of the engine 10.
A control unit 30 is operatively coupled with the throttle position sensor
18, the throttle switch 20, the accelerator position sensor 24, the
accelerator switch 28, and the engine revolution sensor 28. The control
unit 30 is of the microcomputer based control module including as usual
input interfaces 32 and 34, a CPU (central processing unit) 38, a memory
37, i.e. ROM and RAM, and an output interface 38. The signals TSS and ASS
generated from the throttle switch 20 and the accelerator switch 26,
respectively, are fed to the input interface 32. The signals .theta.A and
.theta.B generated from the throttle position sensor 18 and the
accelerator position sensor 24, respectively, are fed to the input
interface 34. The control unit 30 is operative to develop the control
signal CS1 as a predetermined function of the accelerator pedal 22. The
control signal CS1 is transmitted to the actuator 16 via the output
interface 38 for varying the position of the throttle valve 14. The
control unit 30 is operative to develop a control signal CS2 for
illuminating the alarm light 27.
The control unit 30 monitors an operation of the throttle valve 14 during
an engine operation. The control unit 30 is operative to determine that
the throttle valve 14 has failed to operate normally when the throttle
switch 20 fails to shift to the ON state thereof after the accelerator
switch 26 has shifted to the ON state thereof. Specifically, the control
unit 30 is operative to conduct a test routine, when the control unit 30
determines that the accelerator switch 28 operates normally, to determine
whether or not the throttle valve 14 operates normally. This test routine
will be explained later by referring to FIG. 6.
The control unit 30 performs a diagnostic test for detecting whether or not
the accelerator switch 26 operates normally during the engine operation.
Specifically, the control unit 30 is operative to determine whether or not
the actual position signal .theta.A is equal to or less than a
predetermined value .theta.1, and then whether or not the actual position
signal .theta.A continues to be equal to or less than the predetermined
value .theta.1 for a first predetermined period of time P1.
As illustrated in FIG. 3, if the predetermined value .theta.1 is 1.4
opening degrees, the control unit 30 determines whether or not the actual
position signal .theta.A is equal to or less than 1.4 opening degrees and
whether or not the actual position signal .theta.A continues to be equal
to or less than 1.4 opening degrees for the first predetermined period of
time P1, e.g. three seconds.
The control unit 30 is operative to determine whether or not the throttle
switch 20 is in the ON state thereof after the control unit 30 determining
that the actual position signal .theta.A has continued to be equal to or
less than the predetermined value .theta.1 for the first predetermined
period of time P1. In the ON state of the throttle switch 20, the actual
position signal .theta.A is a predetermined second value .theta.2 less
than the predetermined value .theta.1. In FIG. 3, the throttle switch
shifts to the ON state in which the actual position signal .theta.A is 1.0
opening degrees and the predetermined second value .theta.2 is equal to or
less than 1.0 opening degrees. The control unit 30 is operative to
determine whether or not the throttle switch 20 continues to take the ON
state thereof for a second predetermined period of time P2, e.g. three
seconds. The second predetermined period of time P2 may be a different
value from the first predetermined period of time P1.
In addition, the control unit 30 is operative to determine whether or not
the accelerator switch 26 fails to take the ON state thereof after the
control unit 30 determining that the throttle switch 20 has continued to
take the ON state thereof for the second predetermined period of time P2.
FIG. 3 shows a timing when the accelerator switch 26 shifts to the ON
state thereof, which is after the timing when the throttle switch 20
shifts to the ON state thereof. The control unit 30 determines whether or
not the accelerator switch 26 continues to fail to take the ON state
thereof for a third predetermined period of time P3, e.g. ten seconds. The
third predetermined period of time P3 is greater than the first and second
predetermined periods of time P1 and P2.
The control unit 30 is operative to determine that the accelerator switch
26 fails to operate normally in response to the control unit 30
determining that the accelerator switch 26 has continued to fail to take
the ON state thereof for the third predetermined period of time P3 after
the throttle switch 20 has continued to take the ON state thereof for the
second predetermined period of time P2.
FIGS. 2A and 2B are a flow diagram implementing the diagnostic test. This
test is repeatedly executed at regular intervals during the engine
operation. The test routine begins at a start point 400. Logic flow then
goes to a decision block 402 where an interrogation is made whether or not
the actual position signal .theta.A of the throttle position sensor 18 is
equal to or less than the predetermined value .theta.1. If the
interrogation is in affirmative, the logic flow goes to a block 404 where
time T1 for which the actual position signal .theta.A continues to be
equal to or less than the predetermined value .theta.1 is measured. The
time T1 is updated by adding an increment .DELTA.T (delta T) to the time
T1 measured in the preceding execution of the test routine. The logic flow
then goes to a decision block 408 where an interrogation is made whether
or not the time T1 becomes equal to or more than the first predetermined
period of time P1, e.g. three seconds. If the interrogation is in
affirmative, the logic flow goes to a block 408 where a flag F1 is set,
indicating that throttle position condition is met. If, at the block 402,
the interrogation results in negative, the logic flow goes to a block 410
where the time T1 is reset at zero and then goes to a block 412 where the
flag F1 is cleared indicating that the throttle position condition is not
met. Also if, at the block 406, the interrogation results in negative, the
logic flow goes to the block 412 where the flag F1 is cleared. The logic
flow then goes to a decision block 414 where an interrogation is made
whether or not the throttle switch 20 is in the ON state thereof. If the
interrogation is in affirmative, the logic flow goes to a block 418 where
time T2 for which the throttle switch 20 continues to take the ON state
thereof is measured. The time T2 is updated by adding an increment
.DELTA.T (delta T) to the time T2 measured in the preceding execution of
the test routine. The logic flow then goes to a decision block 418 where
an interrogation is made whether or not the time T2 becomes equal to or
more than the second predetermined period time P2, e.g. three seconds. If
the interrogation is in affirmative, the logic flow goes to a block 420
where a flag F2 is set, indicating that throttle switch condition is met.
If, at the block 414, the interrogation results in negative, the logic
flow goes to a block 422 where the time T2 is reset at zero and further
goes to a block 424 where the flag F2 is cleared indicating that the
throttle switch condition is not met. If, at the block 418, the
interrogation results in negative, the logic flow goes to the block 424
where the flag F2 is cleared.
The logic flow then goes to a decision block 428 where an interrogation is
made whether or not the flag F1 is kept set. If the interrogation results
in affirmative, the logic flow goes to a decision block 428 where an
interrogation is made whether or not the flag F2 is kept set. If the
interrogation results in affirmative, the logic flow goes to a block 430
where time T3 for which the flag F1 and the flag F2 are kept set,
respectively, is measured. The time T3 is updated by adding an increment
.DELTA.T (delta T) to the time T3 measured in the preceding execution of
the test routine. If, at the blocks 426 and 428, the interrogations result
in negative, respectively, the logic flow goes to a block 432 where the
time T3 is reset at zero and further goes to a return point 434 to start
the routine again from the start point 400. Subsequent to the block 430,
the logic flow goes to a decision block 438 where an interrogation is made
whether or not the accelerator switch 26 is in the ON state thereof. If
the interrogation is in affirmative, the logic flow goes to the return
point 434. If, at the block 436, the interrogation results in negative,
the logic flow goes to a decision block 438 where an interrogation is made
whether or not the time T3 for which the accelerator switch 26 continues
to take the ON state thereof is equal to or more than the third
predetermined period of time P3, e.g. ten seconds. If the interrogation
results in affirmative, the logic flow goes to a block 440 where an alarm
is made to indicate that the accelerator switch 26 fails to operate
normally. In this embodiment, the alarm light 27 is illuminated informing
a driver of a vehicle of occurrence of the failure of the accelerator
switch 26. The logic flow then goes to a block 442 where the time T1, the
time T2, the time T3 are reset at zero and the flag F1 and the flag F2 are
cleared, and further goes to the return point 434 and the routine begins
again from the start point 400. If, at the block 438, the interrogation is
in negative, the logic flow goes to the return point 434 to repeat this
routine from the start point 400.
Referring to FIGS. 4 and 5, a second embodiment of the testing apparatus
according to the invention, will now be explained. In this embodiment, the
internal combustion engine is a diesel engine 100.
As illustrated in FIG. 4, the testing apparatus includes an adjusting lever
102 acting as the power control element positionable in response to a
control signal to establish various states of combustible charge to be
combusted in the diesel engine 100. The adjusting lever 102 has one end
disposed within an fuel injection pump 104 as described later. An actuator
106, e.g. stepping motor, is provided for actuating the adjusting lever
102 to vary a position which the adjusting lever 102 takes. The actuator
108 is operatively coupled with a control unit 108. The control unit 108
is operatively coupled with an adjusting lever position sensor 110, an
adjusting lever switch 112, an accelerator position sensor 114, an
accelerator switch 116, and an engine revolution speed sensor 118. The
adjusting lever position sensor 110 is operatively coupled with the
adjusting lever 102 to provide an actual position signal .theta.A
indicative of the position of the adjusting lever 102. The adjusting lever
switch 112 is shiftable to a predetermined state, that is, a closed state,
when the position of the adjusting lever 102 is equal to or less than a
predetermined position. In the second embodiment, the closed state of the
adjusting lever switch 112 is an ON state. The adjusting lever switch 112
continues to generate a signal while it is in the ON state. Reference
numeral 120 denotes an accelerator or gas pedal operatively connected with
the accelerator position sensor 114 and the accelerator switch 116.
Reference numeral 122 denotes an alarm light. The accelerator position
sensor 114, the accelerator switch 116, the accelerator pedal 120, and the
alarm light 122 are similar to the accelerator position sensor 24, the
accelerator switch 26, the accelerator pedal 22, and the alarm light 27,
as described in the first embodiment, and therefore detailed explanations
therefor are omitted. The adjusting lever 102 is operatively connected
with a sleeve 124 mounted to the fuel injection pump 104 as shown in FIG.
7. As illustrated in FIG. 7, the sleeve 124 is fit on a plunger 126
disposed within the fuel injection pump 104. The plunger 126 has a fuel
passage 128 for distributing fuel to engine cylinders (not shown). The
plunger 126 has spill ports 130 communicating with the fuel passage 128
and open to an outer peripheral surface of the plunger 126. The sleeve 124
is displaceable in an axial direction of the plunger 126 to vary fuel
discharge from the spill ports 130. Depending on the axial displacement of
the sleeve 124, the plunger 126 has different strokes for providing
suitable fuel injection for engine operating conditions. The sleeve 124 is
operatively connected with a control lever 132 actuated by a centrifugal
force adjusting member (not shown) rotatable in response to engine
operating conditions, and a tension lever 134 connected with the
accelerator pedal 120 via springs 136, 138, and 140. The actuator 106 is
mounted to a casing 142 of the fuel injection pump 104. The actuator 106
includes a rod 144 projecting from and retracting into a housing of the
actuator 106 in response to angular movement of a rotor (not shown)
disposed within the actuator 106. The rod 144 is engaged with the other
end of the adjusting lever 102 which projects outward from the casing 142
of the fuel injection pump 104. The adjusting lever 102 is rotatably
supported on a shaft 146 and operatively connected at the one end with a
rotating lever 148 via the shaft 146. The rotating lever 148 includes a
boss portion receiving the shaft 146 and having on its outer peripheral
surface a cam surface which is contacted with the tension lever 134. The
cam surface is formed by varying steppedly radial dimension of the boss
portion. When the actuator 106 is driven, the rotating lever 148 is
rotated by the projecting and retracting motions of the rod 144 and then
the tension lever 134 is moved. This causes the axial displacement of the
sleeve 124 relative to the plunger 126.
In the second embodiment, the control unit 108 is similar to the control
unit 30 of the first embodiment and performs a test routine as explained
in the first embodiment by using the flow diagram shown in FIGS. 2A and
2B. Therefore, detailed descriptions for the control unit 108 and the
diagnostic test executed by the control unit 108 are omitted.
The control unit 30 or 108 is operative to continuously repeat the
above-mentioned test routine for avoiding making erroneous determination
caused due to detection of operational inconsistency between the throttle
switch 20 or adjusting lever switch 112 and the accelerator switch 26 or
116. FIG. 3 illustrates by shadow the operational inconsistency between
the throttle switch 20 or adjusting lever switch 112 and the accelerator
switch 26 or 116, in which the throttle switch 20 or adjusting lever
switch 112 is in the ON state thereof but the accelerator switch 26 or 116
is in the OFF state thereof.
Further, the control unit 30 or 108 is operative to cancel the
determination that the accelerator switch 26 or 116 fails to operate
normally and make no alarm, unless the determination of failure of the
normal operation of the accelerator switch 26 or 116 has been made
serially in the current execution of the test routine and the preceding
execution thereof during the repeated execution thereof.
Thus, the testing apparatus prevents erroneous determination of state of
the accelerator switch which is caused by detecting operational
inconsistency between the throttle switch or adjusting lever switch and
the accelerator switch. Especially, this apparatus serves for improving
the combustible charge intake operation within an idle speed range of the
internal combustion engine.
FIG. 6 is a flow diagram of the test routine to determine whether or not
the throttle valve 14 fails to operate normally during an operation of a
gasoline engine. Execution of this test routine is repeated at regular
intervals during the engine operation. The test routine begins at a start
point 600. Logic flow goes to a block 601 where there is an interrogation
whether or not the alarm is made, namely, whether or not the accelerator
switch 26 fails to operate normally. If this is the case, the logic flow
goes to a return point 610 to start again the test routine at the start
point 600. If not, the logic flow goes to a block 602 where the actual
position signal .theta.A generated from the throttle position sensor 18
and the position signal .theta.B generated from the accelerator position
sensor 24 are read. Then, the logic flow goes to a block 604 where a
deviation E between .theta.B and .theta.A is obtained as an absolute value
calculated by subtracting .theta.A from .theta.B. The logic flow goes to a
decision block 606 where an interrogation is made whether the deviation E
is greater than a predetermined value E1. The predetermined value E1 is
calculated based on a difference between .theta.B and a target position
signal indicative of a target position which the throttle position sensor
18 is to take. The target position signal is expressed by a function of
.theta.B. If, at the block 606, the interrogation is in affirmative, the
logic flow goes to a block 608 where the alarm light 27 is illuminated and
an instruction to cut fuel feed to all or a part of the engine cylinders
is issued. After the block 608, the logic flow goes to the return point
610.
If, at the block 606, the interrogation results in negative, the logic flow
then goes to a block 612 where the signal ASS generated from the
accelerator switch 26 and the signal TSS generated from the throttle
switch 20 are read. The logic flow goes to a decision block 614 where an
interrogation is made whether the accelerator switch 26 is in the ON state
thereof. If the interrogation is in affirmative, the logic flow goes to a
decision block 616 where an interrogation is made whether the throttle
switch 20 is in the ON state thereof. If, at the block 616, the
interrogation is affirmative, the logic flow then goes to a block 618
where an instruction for a normal throttle control is issued and then to
the return point 610.
If, at the block 614, the interrogation results in negative, the logic flow
goes to the block 618 and then to the return point 610. At the block 616,
if the interrogation results in negative, the logic flow goes to the block
608 and then to the return point 610.
It will be appreciated from the above description that the testing
apparatus of the invention serves for improving an operating performance
of the combustible charge intake system of the internal combustion engine.
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